The present invention relates generally to edge card connectors, and more particularly to connectors that utilize flexible circuitry as the connector contacts and which have an improved card engagement means.
Connectors are well known in the art which provide a connection between a primary circuit board and a secondary circuit board and are commonly referred to in the art as edge card connectors. These connectors typically include an insulative housing having a slot extending lengthwise within the housing that receives an edge of the secondary circuit card and a plurality of contacts on opposing sides of the slot. The contacts of these connectors may be individual contacts that are stamped and formed, or they may be formed on a resilient continuous stratum, in the form of flexible film or flexible printed circuitry ("FFC"). With the use of FFC, very small pitches, i.e., the contact to contact spacing of about 0.3 mm may be obtained.
When FFC is incorporated in edge card connectors, such as those shown in U.S. Pat. No. 3,614,707 issued Oct. 19, 1971 and U.S. Pat. No. 5,427,533 issued Jan. 27, 1995, the FFC extends over the connector card-receiving slot so that a circuit card may be inserted into and withdrawn from the connector slot as needed. As described in U.S. Pat. No. 5,679,018 for "Circuit Card Connector Utilizing Flexible Film Circuitry" assigned to the assignee of the present invention, an edge card connector utilizing FFC has a circuit card-engaging means that utilizes elongated spring members that extend the length of the connector. These spring members are used to apply a contact force between the conductive traces of the FFC and the contact traces formed on the circuit card that oppose the FFC.
Although reliable, it has been discovered that this style of connector construction has some disadvantages, particularly in obtaining substantial compliance with the circuit card contact traces. Due to the fact that the particular spring members are continuous over the length of the connector, it is difficult for the spring members to exert a uniform contact force for the entire length of the circuit card when variations in the thickness of the circuit card occur. In order to counteract this compliance problem, a resilient layer such as is described in U.S. Pat. No. 5,505,625, issued Apr. 9, 1997 and assigned to the assignee of the present invention, may be applied to the spring members. This extra layer increases the complexity and cost of manufacture of such connectors.
Accordingly, a need for a FFC connector with increased compliance characteristics exists. Such a connector is not present or suggested by the prior art.